$a= '<td><a href="http://localhost/_ftp_file_mapper.php?dosyatipi=musteri&id=336926&dosyaadi=336926-1583339229.jpg&dosyaid=306122" class="btn btn-xs btn-info" target="_blank"><i class="icon-download-alt"></i></a></td>';
preg_match_all('#<td><a href="(.*?) class="btn btn-xs btn-info" target="_blank"><i class="icon-download-alt"></i></a></td>#',$a,$link);

echo "<pre>";
print_r($link);